We recently spoke with Dr. Joseph Ford about optical MEMS. In this detailed interview, Dr. Ford reviews the history of optical MEMS and discusses possible future trends.
MEMS Investor Journal: When were optical MEMS first introduced and what were the original applications?
Joseph Ford: Displays were first major application and still dominates the market. Texas Instrument’s Digital Light Projector (DLP) was championed by Dr. Larry Hornbeck, who filed his first patent in 1982 on a Deformable Mirror Light Modulator to display images for coherent optical transforms. It took five years to evolve from cloverleaf structures to the digital "teeter totter," and another ten to create the first DLP product.
The Grating Light Valve was an entirely different approach to display using diffraction from a linear array of MEMS ribbons. This technology arose out of Stanford in the mid 1990s and was ultimately licensed by Sony (Optics and Photonics News, pp. 50-53, Sept 2002).
Another early application of optical MEMS was as individual analog scan mirrors, which had commercial uses for compact barcode readers and for retinal scanning heads-up displays. One example was Microvision’s work with the University of Washington to develop resonant scanners for heads-up displays.
Texas Instruments developed individual two-axis scan mirrors, and arrays of electrostatically actuated mirrors were fabricated by several universities, including Berkeley’s Sensors and Actuators Center.
But by far the largest investment and technology driver in optical MEMS was fiber optic components for telecom. This started in 1994, when Bell Laboratory’s Advanced Technology Research Department demonstrated an inexpensive optical modulator for fiber-to-the-home using a MEMS tunable etalon. I lead a small team that built the first MEMS attenuator, spectral equalizer (1996) and wavelength switch (in 1997). Another group within Bell Labs also built the first large-scale beamsteering crossconnect. (See Goossen et al, IEEE Photonics Technology Letters, vol. 6, p.1119, 1994, and Ford et al, IEEE LEOS 1997 Annual Meeting, paper PD2.3)
By the late 1990s, many other universities and companies large and small were developing MEMS fiber components, and by 2001 there were a variety of Telcordia-qualified products selling to eager telecom system integrators. Orders exceeded production capacity by 10 to 100 times, so it seemed like good business strategy to invest heavily in production facilities and tooling. It was an exciting time.
MEMS Investor Journal: How was the market for optical MEMS affected by the troubles in the telecom industry in the early part of this decade?
Joseph Ford: The telecom market crash was catastrophic for optical MEMS, because the technology was on the "cutting edge," providing solutions for extremely high bandwidth networks. Service providers like Sprint and Worldcom – remember Worldcom? – halted new system deployments, then the system integrators like Nortel and Ciena cancelled orders and cut procurement for all but maintenance of previously fielded systems. Component sales fell by 99%, eventually killing off all but the strongest of the MEMS startups, and leading to layoffs at all of the large R&D labs. Telecom had pulled in most of the engineers working in the field, and so when that market collapsed, most these people found opportunities in other areas: other commercial applications, defense, and academia.
MEMS Investor Journal: Which applications have survived and are on the market today?
Joseph Ford: In telecom the most conspicuous MEMS survivors are well-established component manufacturers JDSU and DiCON, sales of the simplest components (protection switches and attenuators) where MEMS had already showed superior cost, footprint, and reliability over the bulk-optomechanical components they replaced. The more advanced MEMS devices are still available from surviving startup companies: crossconnects from Glimmerglass and Calient, spectral equalizers from Polychromix and Lightconnect, and wavelength switches from Capella and MetConnex. Their products have been designed into the next-generation optical networks, and component sales will revive when these systems are deployed.
There are a number of successes outside of telecom. Texas Instruments’ DLP display continued to build it’s market share, and has grown to dominate the liquid crystal competition. MEMS bar-scanners were successfully commercialized by Intermec.
A MEMS-based spectrometer derived from the spectral equalizer is sold by Polychromix, and adaptive optic systems for aberration correction are available from OKO Technology and AOMEMS. These are currently used in scientific instruments, but may find their way to high-end consumer products. The optical scanners and displays I mentioned earlier are also heading for volume production.
MEMS Investor Journal: Which optical applications are likely to be commercialized over the next 3-5 years?
Joseph Ford: Telecom’s enormous investment brought optical MEMS to a fully qualified production technology. With these costs "paid in advance", this established engineering base is being applied to profitable niche markets, and also to risk-averse or short lead-time mass markets, both of which could probably not otherwise have supported the necessary development.
There are defense applications involving secure free-space communications and optical "tags" where MEMS can provide active beam steering and retro-modulators. Remote optical sensing, including chemical and motion tracking sensors, will be crucial for homeland defense and are likely to be deployed in large quantities. Optical MEMS enables compact integration of optical source, detector, beam-forming and tracking, and will be found in various specific applications.
However, the biggest commercial market for optical MEMS technology is in consumer camera and display technology. Miniaturized cameras require autofocus, image stabilization and zoom capability. MEMS technology offers inexpensive integration of all these functions, and will certainly play a leading role in snapshot cameras, computers, and cell phones. Qualcomm is a leading technology player, and their recent purchase of MEMS display company Iridigm is a strong indicator.
Texas Instruments-style projection displays are a large market, but still small compared to the potential for handheld displays (laptop computer, PDA and cellphone).
MEMS Investor Journal: In general, could you comment on the lessons learned and future trends for optical MEMS?
Joseph Ford: The telecom boom and bust, painful as it was to those of us involved, caused a technical leap forward that will be exploited by a much more diverse and stable market base, and which in turn will fund new investment in research and development.
The future for optical MEMS will certainly hold surprises, but one major area already under investigation is to integrate our current microfabrication and micropositioning technology with nanophotonics, artificial structures with features much smaller than the wavelength of light. Optical MEMS devices based on tilting mirrors need to move by tens of microns and are limited to about 50 KHz operation, while devices based on interferometry and diffraction have sub-micron actuation and operate up to 16 MHz. The fusion of nanophotonics with MEMS will enable optical devices with nanometer-scale actuation and potentially GHz response. It is, once again, an exciting time to be working in optical MEMS.
Dr. Joseph Ford is an Associate Professor of ECE at the University of California San Diego, where he leads the Photonics Systems Integration Laboratory.
Dr. Ford was a member of Bell Labs Advanced Photonics Research Department from 1994 to 2000, where he developed MEMS and optoelectronic components including the first MEMS variable attenuator, dispersion compensator, spectral equalizer, and wavelength add/drop switch.
In 2000 he joined Optical Micro-Machines, becoming Chief Scientist in 2001 before joining UCSD in 2002. Dr. Ford is co-author on 45 United States patents and over 100 journal articles and conference proceedings. Dr. Ford was General Chair of the first IEEE Conference on Optical MEMS in 2000, and will be Program Co-Chair for the 2006 Optical Fiber Communications Conference.
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